春水堂视频

Night Light Development Index correlates strongly with the U.N. Human Development Indicator, other welfare metrics

Gross Domestic Product and its cousin, GDP per capita, have long been the most widely accepted measures of national and human wellbeing around the globe. But for nearly as long, GDP and per-capita GDP have been seen as deeply flawed.

After all, GDP鈥攁 number representing the total amount of goods and services produced by a nation within a specified period of time鈥攄oesn鈥檛 distinguish spending on, say, education and cigarettes. Likewise GDP doesn鈥檛 measure anything without a market price attached and completely disregards the 鈥渋nformal economy鈥� volunteering, household work, childcare, subsistence agriculture and more.

"Researchers are able develop ratios of data from nighttime satellite imagery to GDP and see where there are discrepancies.听The satellite imagery tracks closely with broader measures of human wellbeing such as the so-called 鈥榟appiness index and the U.N.鈥檚 Human Development Indicator.鈥�

Another limitation: GDP measures total economic activity, but not the distribution of that activity, also referred to as 鈥渋nequality.鈥� That important distinction is currently at the center of political debate in the United States, as incomes disparity has widened significantly in recent decades.

Also, governments too often manipulate GDP, and methods of determining GDP vary widely around the globe.

鈥淭here is no standardized method of for gathering data (on GDP) throughout the world,鈥� says Tilottama Ghosh, a research 听associate at CU-Boulder鈥檚 Cooperative Institute for Research in the Environmental Sciences and co-author of 鈥淯sing Nighttime Satellite Imagery as a Proxy Measure of Human Well-Being,鈥� published in the November issue of Sustainability.

But Ghosh has been working with other researchers from the National Oceanic and Atmospheric Administration, the University of Denver and elsewhere to demonstrate that nighttime satellite imagery can serve as an effective proxy measure of human well-being.

Evaluating imagery from the U.S. Defense Meteorological Satellite Program, which goes back to 1992, and other sources, the research team starts with the general proposition that more lights on a satellite image鈥攎easured in pixels per square kilometer鈥攃orrelate with higher levels of development.

Think of the famous photos from space showing North Korea to be almost a black hole while South Korea is ablaze with light. Or the comparison between a brightly lit Tokyo and the heart of Africa.

But the work is more refined than that. For example, the researchers are able develop ratios of data from nighttime satellite imagery to GDP and see where there are discrepancies.

The satellite imagery tracks closely with broader measures of human wellbeing such as the so-called 鈥渉appiness index鈥� and the U.N.鈥檚 Human Development Indicator.

鈥淥ur Night Light Development Index correlates strongly with the long-established metric of the HDI used by the United Nations that is based on multi-dimensional composite of things like GDP/capita, life expectancy, and average years of education per capita,鈥� says Paul C. Sutton of the Department of Geography and the Environment at Denver University, one of Ghosh鈥檚 co-authors.

What鈥檚 more, satellite provides data more immediately than on-the-ground surveys of well-being, which can take years.

鈥淭hese proxy measures are updated much more frequently,鈥� Ghosh says.

Development is not without its consequences, however. Satellite imagery also shows what 听Sutton calls an 鈥渆cological deficit.鈥� In other words, zero pixels per square kilometer shine forth from the deepest Amazon, while crowded cities, with their attendant issues of pollution and resource depletion, blaze with light.

鈥淭he more developed countries of the world are taking more from the environment,鈥� she says.

To date, a square kilometer has been about the highest resolution available to measure light output. But satellites of the National Polar Orbiting Partnership between NASA and NOAA have since 2011 provided higher resolution imagery.

鈥淥ne of our main objectives is higher-resolution data, to be able to refine the measurements further. Once these data become available 鈥� we鈥檒l have much superior quality for estimating socio-economic variables,鈥� Ghosh says.